During the past year construction of a large cage has been completed at the University of Illinois Biologic Research Laboratory. The cage will house a colony of Guinea Baboons to enable investigation of the group as a model for certain types of macular degeneration seen in man. The ophthalmic changes (including fluorescein angiography) will be closely correlated with the following: 1. Behavioral abnormalities including visual acuity; 2. Electrophysiology; 3. Pathology (light and electron microscopy); and 4. Biochemistry. Retinal dystrophies are a leading cause of blindness in man. A nonhuman model will greatly advance our knowledge of the pathogenesis of this group of diseases. Histopathologic and electron microscopic studies on the developing lesion will advance our knowldege of the pathologic process occurring. Extensive biochemical testing will hopefully reveal abnormal chemistries responsible for the fundus change and offer an understanding of the disease on which to base a therapeutic modality.